1. Field of Invention
The field of the currently claimed embodiments of this invention relates to electro-chemical sensors, and more particularly to electro-chemical sensors that have analyte-responsive semiconductors.
2. Discussion of Related Art
In recent years, various chemical sensors based on organic field effect transistors (OFETs) have been proposed and investigated, as they possess advantages of easy tuning of the chemical and physical properties, low-cost processing, and flexible mechanical properties.1,2 Most OFETs exposed to various chemical compounds such as polar solvents including water vapor, and particularly, nitroaromatic explosives, showed decreased output current and mobility.1,3-11 The degradation of the transistor performance by exposure to the chemical compounds was caused by reduced charge transport dipoles causing charge trapping at grain boundaries.1,5 
However, even though many organic semiconductors have been shown to result in current decreases when environmental agents contact them as voltage is applied, they have limited specificity since the responses are similar. Also, the absolute current level is limited to the non-exposed state. There thus remains a need for improved electro-chemical sensors.
References for Background Section
(1) See, K. C.; Becknell, A.; Miragliotta, J.; Katz, H. E. Adv Mater 2007, 19, 3322.
(2) Torsi, L.; Tanese, M. C.; Cioffi, N.; Gallazzi, M. C.; Sabbatini, L.; Zambonin, P. G.; Raos, G.; Meille, S. V.; Giangregorio, M. M. J Phys Chem B 2003, 107, 7589.
(3) Huang, J.; Miragliotta, J.; Becknell, A.; Katz, H. E. J Am Chem Soc 2007, 129, 9366.
(4) Huang, J.; Sun, J.; Katz, H. E. Adv Mater 2008, 20, 2567.
(5) Huang, J.; Dawidczyk, T. J.; Jung, B. J.; Sun, J.; Mason, A. F.; Katz, H. E. J Mater Chem 2010, 20, 2644.
(6) Royer, J. E.; Lee, S.; Chen, C.; Ahn, B.; Trogler, W. C.; Kanicki, J.; Kummel, A. C. Sensor Actuat B-Chem 2011, 158, 333.
(7) Zhu, Z. T.; Mason, J. T.; Dieckmann, R.; Malliaras, G. G. Appl Phys Lett 2002, 81, 4643.
(8) Li, D. W.; Borkent, E. J.; Nortrup, R.; Moon, H.; Katz, H.; Bao, Z. N. Appl Phys Lett 2005, 86.
(9) Crone, B.; Dodabalapur, A.; Gelperin, A.; Torsi, L.; Katz, H. E.; Lovinger, A. J.; Bao, Z. Appl Phys Lett 2001, 78, 2229.
(10) Chang, J. B.; Liu, V.; Subramanian, V.; Sivula, K.; Luscombe, C.; Murphy, A.; Liu, J. S.; Frechet, J. M. J. J. Appl. Phys. 2006, 100.
(11) Torsi, L.; Marinelli, F.; Angione, M. D.; Dell'Aquila, A.; Cioffi, N.; De Giglio, E.; Sabbatini, L. Org Electron 2009, 10, 233.